Sunday, 29 November 2009

Flight test text

As many people don't seem to want to register on the Av8magazine site, I have copied the text here:
This is going to be a very difficult thing to write about!
On Thursday the 19th of November I found myself at the Aircreation factory in Aubenas, France. The weather was a warm 16 degrees C with light winds. As I stood in front of the gold painted Tanarg fitted with the revolutionary BioniX wing, I thought that this was going to be one of those days that I would remember for a long time.
The Tanarg is the standard Rotax 912S engined flexwing, fitted with the Enigma dash and a ballistic parachute. The MTOW for this machine is 472 kgs here in France. There is very little difference between this and the Tanarg that I normally fly, apart from the parachute fitted to this one and the iXess15 wing fitted to mine. I had considered fitting an iXess13 wing to mine for a little extra speed, but would loose out on the short strip performance. Then there is the BioniX wing!
The BioniX incorporates a few bits of technology which are not normally seen on flexwing microlights. First is the “Corset” as Aircreation describe it. Instead of having a trim wheel on the right of the control bar, there is a handle to turn. This tightens the cables in the corset and changes the profile of the wing. On a standard trim wheel the wing is set up for a particular speed and any deviation from that speed, be it faster or slower, is a compromise. By changing the profile, as the BioniX does, the optimum speed is changed from slow to fast or vice versa, this means that in any position of the corset the wing is flying efficiently at different speeds. A conventional trim on normal flexwings pulls up the trailing edge of the wing and moves the bar forward or rearward so that the pilot does not have to hold any pressure to fly at differing speeds. The “Corset” changes the profile so that the control bar stays in the same position whether it is in fast or slow mode. This has the advantage of allowing full forward or rearward movement of the bar at any trim speed. The nearest comparison to this on military aircraft is the swing wing design.
Another interesting feature is that the wing has vortex inducers on top of the leading edge on the inboard part of the wing. Then there are the quick release baton tips on the trailing edge of the wing, which look more aerodynamic than the usual tied chords.
When it was time to fly the aircraft, the Aircration instructor sat in the back with me in the front and 40 liters of fuel on board. We taxied out to the short runway. After few checks, one to make sure that the handle was in the slow position, I pressed the throttle and within 60 meters or so was airborne. I climbed out at about 6 to 7 meters per second (1200 to 1400 ft/min), this was impressive compared to my wing. We leveled out at around 1200 feet and I played with the throttle. At a mere 65 to 70 kmh (40 to 45 mph) the wing felt completely in control, it was light in both roll and pitch and felt like it was flying rather than getting close to the stall – which it was not. I set the hand throttle at 4000 rpm and let it build up speed till it was straight and level at just over 80 kmh (50 mph). With the throttle fixed I turned the “go faster” handle and kept it level. When in the taught (fast) position it was flying at around 125 kmh (75 mph), the wing felt exactly the same as in the slow mode, very light and stable. At this point I opened the throttle and put a little back pressure on the control bar to keep the aircraft at the same level and found myself at just over 150 kmh (94 mph). The only difference was the buffeting around my flying helmet! It would have been happy sitting there all day. But speed is not what this wing is about.
We turned towards the airfield and slowed the machine down to 65 kmh again for the approach. It just floated toward the end of the short runway. There was no swinging about with the slight winds and the control felt very secure. Just above the end of the runway the instructor told me to push the bar out to the front strut, this is not something that I would normally do as a stall would result in a heavy landing, but not the BioniX, it just flew slower and slower until it touched down. I estimate the distance from rear wheels touching the runway to full stop as less than 30 meters.
We did not taxi back to the end of the runway for another take off, we just opened the throttle and were off again in no time. Aubenas is in a mountainous area with hills all around and I expected a little turbulence when flying low, but if there was any, the BioniX did not react to it at all.
On the second flight, I tried a spiral dive in the slow mode and the same in the fast mode, both felt fully controlled and as if the machine knew what I wanted to do before I did. To fly a fast, stable and lightly controlled microlight and then fly a slow stable microlight in one flight has to be a strange experience for any flexwing pilot.
I checked the fuel after the hours flight and would expect that it used around 10 liters per hour. This is on a par with the wing on my machine, but at a slightly higher weight. In normal flying, I would think that with less drag the BioniX may be a bit more economical than mine in the cruise.
The Tanarg has to be the most comfortable flexwing on the market with the large, well padded seats and the fully adjustable footrests, the BioniX wing is just the icing on the cake. The combination has now also become the most versatile. I can imagine that this would make an ideal aircraft wing combination for a small flying school where the instructor trains on the machine in the slow mode, and then goes touring in it too.
That afternoon, my wife went up in the back seat, she is not a pilot but a passenger, and has only been that for about 2 years. The instructor switched the engine off in the air and performed some manoeuvres to show her how it flies. They landed without the engine. She commented afterwards that it was the smoothest flight that she had ever had, and that it will be a great photographic platform for her due to the slow speed performance.
The instructor has a Tanarg of his own. He has two wings for it, an iXess 15 and a 13, one he flies in the Alps and one that he flies near Aubenas. His comment that he will sell both and have one BioniX, is testament that this is a very versatile wing.
It is very difficult to put the experience of this flight into words and I would encourage others to fly the BioniX to feel the difference between this and “normal” wings, I have not yet met anyone who has flown it and does not think that it must be the future of flexwing microlights.
Should anyone want to order a BioniX, it will fit any Aircreation Tanarg trike, but be quick because there will be a large order book.
Two interesting web pages about the BioniX can be found on the Aircreation website at:
http://www.aircreation.fr/anglais/Products/FAQBioniX/tabid/187/language/fr-FR/Default.aspx
and http://www.aircreation.fr/anglais/Products/Wings/BioniXWing/tabid/186/language/fr-FR/Default.aspx.

2 comments:

Scott Alexander Gabriel said...

Thanks a lot, Bob.

Daryl said...

Thats a very interesting report, when will it be here in the UK? If they can get that top end up to circa 85 to 90mph I think they will have created a significant competitor to the P&M R wing.

The speed is the key (IMHO) they dont have to beat it, but getting well up from the Quik wing at 75 - 80mph and toward the realistic 90 to 100 of the R would see the benifits come home to roost.

I think your right about instructors liking this wing but what is really key here is that its not a kit! of coarse they cant train on those!